Considered a single stock: A group of individuals in a species occupying a well defined spatial range independent of other stocks of the same species. It can be affected by random dispersal movements and directed migrations due to seasonal or reproductive activity.

Spatial Scale: Spatial scale contains a standard term such as Global, Regional (e.g. for the whole Atlantic), sub-regional (e.g. for a part of the Atlantic), national, local (for sub-national levels).

Considered a management unit: An aquatic resource or fishery is
declared as [Fishery] Management Unit if it is
effectively the focus for the application of selected
management methods and measures, within the broader
framework of a management system. According to the FAO
Glossary for Responsible Fishing, "a Fishery Management
Unit (FMU) is a fishery or a portion of a fishery
identified in a Fishery Management Plan (FMP) relevant
to the FMP's management objectives." FMU's may be
organised around fisheries biological, geographic,
economic, technical, social or ecological dimensions ,
and the makeup and attribute of a fishery management
unit depends mainly on the FMP's management
objectives.

Landings from the Firth of Forth fishery are predominantly reported from Scotland, with very small contributions from England. The area is periodically visited by vessels from other parts of the UK. There is a risk that owing to fuel costs vessels which would normally fish further offshore will locate to inshore grounds. The Firth of Forth is close inshore and is of small geographic size so that significant influx of effort will have deleterious effects.

Catches of marketable bycatch fish are small from this area and there are few other species in the area for vessels to target.

Estimated discarding rates are 31% by number in the Firth of Forth in 2008. This arises from the use of mainly small-meshed (80 mm) nets and the population size structure which appears to arise from slower growth. Local markets for small whole Nephrops are seasonally important.

Changes in fishing technology and fishing patterns

The Firth of Forth resident fleet contains numerous small boats which are generally restricted to more sheltered inshore waters. There are, however, observations of shifts of Nephrops fishing by larger vessels from the fleet to grounds such as the Devil’s Hole ( an offshore ground not included as part of a Functional Unit).

Assessment

Assessment Model

Methodology

Scientific basis

Data and methods

The UWTV survey has been conducted annually since 1993 (no surveys in 1995 and 1997). Monthly market sampling and quarterly on-board observer sampling provides good coverage of length compositions. Potential bias in survey design has been detected and accounted for in the assessment this year (see “Data and methods” section at the start of section 6.4.14.)

Information from the fishing industry

The NSCFP survey (Figure 6.4.14.3) does not include specific information for the Firth of Forth.

Uncertainties in assessment and forecast

General comments are found at the start of section 6.4.14

Comparison with previous assessment and advice

The perception of the stock in 2008 is very similar to that of the stock in 2007

The advice in 2008 was based on recent landings as the UWTV surveys were considered inappropriate to use as absolute indices of abundance. Following the outcome of the benchmark in 2009, the major concerns of the UWTV survey have been addressed and the survey is now considered a reliable estimate of absolute abundance..

The landings forecast for 2010 (<1 567 t) is considerably lower than for 2009 (<2500t). This is due to using Fmax as the target F for this stock in the current advice.

Table 6.4.14.4.3 Nephrops, Firth of Forth (FU 8). Survey indices with and without bias adjustment. Values after 2002 have been adjusted for revised camera parameters

Year

Mean
density

Abundance

95%
confidence
interval

Adjusted for bias

95%
confidence
interval

burrows/m²

millions

millions

millions

millions

1993

0.72

655

167

555

142

1994

0.58

529

92

448

78

1995

1996

0.48

443

104

375

88

1997

1998

0.38

345

95

292

81

1999

0.60

546

92

463

78

2000

0.57

523

83

443

70

2001

0.54

494

93

419

78

2002

0.66

600

140

508

119

2003

0.99

905

163

767

138

2004

0.81

743

166

630

140

2005

0.92

838

169

710

143

2006

1.07

976

148

827

126

2007

0.90

816

156

692

132

2008

1.14

1040

350

881

297

Reference Point

F

reference point

Harvest

ratio

Technical basis

F0.1

8.0%

WKNEPH 2009

Fmax

13.7%

WKNEPH 2009

(unchanged since 2009)

Scientific Advice

Single-stock exploitation boundaries

ICES advises on the basis of exploitation boundaries in relation to high long term yield and low risk of depletion of production potential that the Harvest Rate for Nephrops fisheries should not exceed Fmax. This corresponds to landings of no more than 1 567 tonnes for the Firth of Forth stock.

To protect the stock in this Functional Unit, management is required to be implemented at the Functional Unit level.

The advised landings for 2010 imply a reduction of 37% relative to the 2008 landings (2 500 t). ICES advice is for Fmax instead of F0.1 because increased landings in earlier years have coincided with an increase in stock implying perhaps that the present level of exploitation could be sustainable. Even though in the longer term the differences in total catch are expected to be small, the move to F0.1 as a target would imply significant initial reductions in catch. In this case a stepwise approach could be considered. A reduction of the catch corresponding to Fmax could be an intermediate step toward F0.1 (as a proxy for Fmsy). Alternatively, a constraint on the year to year change in catches as is typical of management plans and the Communication on Fishing Opportunities for 2010 [COM (2009) 224] might be considered.

Nephrops discard rates in this Functional Unit are high and there is a need to reduce these and to improve the exploitation pattern. An additional reason for suggesting improved selectivity in this area relates to bycatch. It is important that efforts are made to ensure that other fish are not taken as unwanted bycatch in this fishery which uses 80mm mesh. Larger square mesh panels implemented as part of the Scottish Conservation Credits scheme should help to improve the exploitation pattern for some species such as haddock and whiting.

Biological State and Trend

State & Trend Descriptors

Partner

FIRMS

Exploitation rate

Undefined

Uncertain/Not assessed

Abundance level

Undefined

Uncertain/Not assessed

The evidence from the UWTV survey suggests that the population has been at a relatively high level since 2003. The UWTV survey information, taken together with information showing stable mean sizes, suggest that the stock is being exploited sustainably.